This application claims the benefit of German Patent Application Ser. No. 101 27 219.7, filed May 23, 2001.
The invention relates to a cooling system for an internal combustion engine that has at least two cylinder rows, such as a V-engine for a motor vehicle. The coolant system includes a coolant radiator and a thermostat valve for controlling the amount of coolant flowing from the coolant outlets of the cylinder rows through the coolant radiator, or through a bypass around the coolant radiator, and back to the coolant inlets of the cylinder rows.
Internal combustion engines that have at least two cylinder rows require an increased coolant conducting capacity, because the coolant flowing from each of the cylinder rows must be combined at a point upstream of the coolant radiator in order to permit the coolant to be conducted either through the coolant radiator or through a bypass line. When the coolant is conducted transversely through the cylinder heads of a V-engine that has been installed in the direction of travel (as of a vehicle), and the coolant radiator is installed transversely to the direction of travel, it has heretofore been necessary for structural reasons to conduct the coolant through an elaborate system of conduits in order to achieve an appropriate coolant flow rate, particularly with respect to the combination of coolant flowing from each cylinder row. What is needed, therefore, is a cooling system wherein the coolant flow path is simplified and the requirement of increased coolant conducting capacity is lessened.
It is accordingly an object of the present invention to provide a cooling system whose working volume is reduced, which permits the design of the coolant conduit system to be simplified, and which permits the flow path of coolant to be as straight as possible.
This object is achieved in the present invention, a cooling system for an internal combustion engine with at least two cylinder rows, such as and particularly a V-engine. The cooling system has a coolant radiator and a thermostat valve for controlling the amount of coolant flowing from the coolant outlets of the cylinder rows through the coolant radiator or through a bypass around the coolant radiator, and back to the coolant inlets of the cylinder rows. In the present invention, the coolant outlet of one of the cylinder rows is directly connected with the inlet of the coolant radiator, the coolant outlet of another of the cylinder rows is directly connected with the bypass inlet of the thermostat valve, and an intermediate, bi-directional coolant line is present between the bypass inlet of the thermostat valve and the inlet of the coolant radiator.
Depending on the way in which the thermostat valve is set, a portion of the coolant can be allowed either to flow through or to bypass the coolant radiator by changing the direction in which the coolant flows through the intermediate line. Since only that portion of the amount of coolant flowing from one cylinder row flows through the intermediate line, less coolant is needed than in a conventional cooling system, the time required to xe2x80x9cwarm upxe2x80x9d the engine (i.e., for the coolant to reach its optimum temperature) is reduced, and the coolant line leading from the outlet to the thermostat valve may be given a partially reduced cross-section. Moreover, the simplified arrangement of the coolant circuit makes it possible to shorten and straighten the lines leading from the outlet to the radiator and from the radiator to the inlet. This yields a particular advantage when the coolant circuit is designed so that the coolant flows transversely through the cylinder heads of a longitudinally installed V-engine, since, in conventional cooling systems, designing a transverse flow requires a long and complicated line course.
In connection with a further development of the invention, the intermediate line runs directly along the engine housing, thereby permitting space to be saved. Additionally, the intermediate line is advantageously integrated into a distributing component attached to the engine housing. In such an arrangement, it is not necessary to extend hoses close to the engine, and the required structural space is reduced.
In still a further development of the invention, a coolant pump is disposed between two cylinder rows, and the thermostat valve is advantageously arranged in the area of the coolant outlet of one of the cylinder rows. A connecting line between the thermostat valve and the coolant pump may be advantageously integrated into the distributing component. These measures result in further space savings.
In another development of the invention, two separate coolant circuits, substantially as described above, are provided, one for the cylinder heads and one for the engine blocks, and at least one of the coolant circuits has an intermediate line between two coolant outlets. In connection with such a so-called xe2x80x9csplitxe2x80x9d cooling system having two coolant circuits, the reduced content of the lines is of particular importance. Also, straight, space-saving lines are particularly important with two coolant circuits.
In yet another development of the invention, the intermediate lines are integrated into a distributing component disposed on the engine housing. A pair of coolant lines connecting the thermostat valves to the coolant pumps of the coolant circuits are likewise advantageously integrated into the distributing component.
These measures result in a substantial space savings, and because the lines are integrated into the distributing component disposed on the engine housing, the number of separate hose connections in the cooling system may be substantially reduced. Moreover, only the distributing component, and not the engine housing, must be changed if a change in the external coolant circuits is desired.
In still a further development of the invention, the respective thermostat valves of the two coolant circuits are arranged so as to be offset from and next to each other in the longitudinal direction of the internal combustion engine. This enables the fines leading thereto to be crossed more easily, while maintaining or improving the reduction in space requirements.
In yet another development of the invention, the distributing component is made in a single piece, with at least one section of a housing of the thermostat valve integrated into the distributing component. The one-piece design of the distributing component in particular helps to avoid the problem of sealing the connection between the housing and any coolant lines. For example, the distributing component can be produced as an injection-molded plastic part.